The present invention relates to unsaturated siloxy compounds which may be used as silica couplers in rubber. The present invention also relates to a silica-filled rubber composition containing unsaturated siloxy compounds and the processing of a sulfur-curable rubber composition containing silica and unsaturated siloxy compounds.
Sulfur containing organosilicon compounds are useful as reactive coupling agents between rubber and silica fillers providing for improved physical properties. They are also useful as adhesion primers for glass, metals and other substrates.
U.S. Patent Nos. 3,842,111, 3,873,489 and 3,978,103 disclose the preparation of various sulfur containing organosilicon compounds. These organosilicon compounds are prepared by reacting
(a) 2 moles of a compound formula
Z-Alk-hal
where hal is a chlorine, bromine or iodine; Z is 
where R1 is an alkyl of 1 to 4 carbon atoms or phenyl and R2 is alkoxy of 1 to 8 carbon atoms; or cycloalkoxy of 5 to 8 carbon atoms; or alkylmercapto with 1 to 8 carbon atoms; Alk is a divalent aliphatic hydrocarbon or unsaturated hydrocarbon or a cyclic hydrocarbon containing 1 to 18 carbon atoms; with
(b) 1 mole of a compound of the formula
Me2Sn
where Me is ammonium or a metal atom and n is a whole number from 2 to 6.
The present invention relates to unsaturated siloxy compounds that do not contain sulfur.